The ruling applies to variety of political and ideological protests, and its outcome was supported by many free-speech advocates, including some supporting abortion rights groups.

At issue was the fairness of using federal laws against racketeering and extortion to go after anti-abortion groups who use, according to the official Court filing, "sit-ins and demonstrations that obstruct public's access" to medical clinics.

Such anti-racketeering and extortion laws have normally been used by federal prosecutors to go after organized crime, and usually involve efforts to illegally obtain "property."

Chief Justice William Rehnquist, writing for the 8-1 majority, noted because the protesters "did not obtain or attempt to obtain [clinic] property, both the state extortion claims and the claim of attempting or conspiring to commit state extortion were fatally flawed."

The National Organization for Women first filed a lawsuit on behalf of the clinics in 1986, and the Court eight years later ruled in its favor. Leaders of the anti-abortion movement, including Operation Rescue and the Pro-Life Action Network, filed a new legal claim the justices heard last Fall.

As far back as the mid 1980s, anti-abortion groups began offering "classes" on clinic protest strategies, ranging from picketing and handling out leaflets, to activists chaining themselves to clinic doors. Some of the demonstrations turned into violent confrontations, including threats and attacks on patients and medical workers, even clinics that were destroyed.

While many of the protest tactics are protected free speech, NOW claimed the confrontations were planned and organized, and represented "a pattern of extortion." The group cited the Hobbs Act, a federal law that made it a crime to obstruct or affect interstate commerce "by robbery or extortion" when "induced by the wrongful use of actual or threatened force, violence and fear."

Anti-abortion groups objected, arguing an economic motive must be present in racketeering cases. The groups claim they did not profit financially from their protests.

The justices concluded anti-abortion activists certainly disrupted the clinics and crimes may have been committed during the protests. "But even when their acts of interference and disruption achieved their ultimate goal of 'shutting down' a clinic that performed abortions, such acts did not constitute extortion," said Rehnquist.